Today, the California Air Resources Board (CARB) formally adopted the Advanced Clean Fleets (ACF) regulation which requires a swift and complete shift away from conventional vehicles to Zero-Emission Vehicles (ZEV) for public agency fleets (among others).

CARB’s Advanced Clean Fleet Regulation


  • First report due to CARB by April of 2024
  • 2024 – 2026: 50% of vehicle purchases must be ZEVs
  • 2027 & beyond: 100% of vehicle purchases must be ZEVs
  • Alternative “Milestone Option” available
  • Limited exemption pathways

CARB’s ACF regulation establishes requirements for public agencies (including public utilities) to purchase a specified percentage of Zero-Emission Vehicles (ZEV) as part of their new vehicle purchases. Starting in 2024, fleet owners are required to add ZEVs per the following schedule. Starting January 1, 2024, 50% of the total number of vehicle additions to the fleet in each calendar year must be ZEVs. Starting January 1, 2027, 100% of the total number of vehicle additions to the fleet in each calendar year must be ZEVs. As an alternative, fleet managers may choose CARB’s Milestone Option which de-links the obligation to integrate ZEVs from the fleet manager’s new-vehicle purchase decision, and instead, establishes a commitment to convert portions of the fleet by target dates specified by the Air Resources Board. To establish a baseline that CARB can effectively monitor, fleet managers are required to provide a complete list and description of all vehicles in the current fleet by April of 2024.

CARB Advanced Clean Fleets Transition Timeline

TerraVerde Energy Can Help

As independent advisors, TerraVerde can help you:

  • Assess your compliance requirements
  • Develop your fleet electrification roadmap
  • Identify funding sources and revenue opportunities

TerraVerde Energy is an independent energy consulting firm proudly supporting California public agencies since 2009 and serves as ACWA’s Preferred Provider for fleet electrification planning services. As your agency looks to identify the path forward, TerraVerde can provide your agency with a clear, actionable assessment of your options, costs, challenges, and opportunities; enabling your team to take an intelligent, risk-mitigated approach to fleet electrification. We would welcome the opportunity to meet with your team and discuss your fleet electrification planning needs. Write to Phil Villagomez, Sr. Vice President ( to get started today.

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